Filling old vent hole

[Molebob]

Whilst renovating my kitchen I exposed an old vent hole that had been stuffed badly with polystyrene packaging and the render has been patched over outside. It is roughly four inches round by eight inches deep.

I considered either sand and cement; or maybe expanding foam. Not sure what is best and obviously want to avoid causing myself damp issues later. This is a 20s house with lime mortar and render.

 

[bitstreams]

What's the wall constructed out of? I it's stone then you should be able to chip a spare bit of stone to roughly fit and then point in around it. Then render over the top.

You could use something pre-mixed like Old House Store's Coarse Stuff - but I think they only sell this in 25kg bags which is obviously way more than you need.

 

[Molebob]

What's the wall constructed out of?

It is a brick wall.